In the end, I decided that I wouldn't spend thousands on a new DSLR system (while also sacrificing myself again to the size and weight of those systems) so I ended up buying the Leica Summarit 75mm. For head shots, it's close enough to the classic 85mm prime lens to be comfortable, while also maintaining the beautiful rendering characteristics I've come to love from the 35mm and 50mm Summarit lenses I own.

That’s not to say I would have liked to have had “a bit more file” to work with when shooting the X-T1.  Well, I may not have gotten the replacement to my X-T1’s but I’ve been shooting the X-Pro2 (codenamed “Leo”) for the past few months.  The first thing I noticed was it was so much “snappier.”  The focus was just crisp and super-accurate.  I’m not saying the X-T1 isn't good I’m just saying this is better.  Files processed through the X-Pro2's image engine were amazingly fast — at least two times faster and probably faster than that.  Whatever this new Sony sensor is doing it’s doing it much faster than the X-T1 doesand exponentially faster than the old venerable X-Pro1.

How does the New 24-35 Sigma Art lens cut the mustard when shooting an 'environmental portrait' at the '35mm' end of the zoom?

Simply put, if I was about to grab the 35mm f/1.4 Art lens, should I be considering the 24-35mm instead? If yes, am I losing anything when I shoot my 35mm Portraits with it? will their be anything noticeable I should be concerned with ?